Safety support pin and system for repair process for instrumented bits and electronics module end-cap for use therewith

ABSTRACT

A spindle assembly for supporting a drill bit for repair. The spindle assembly includes a plurality of stepped segments of ever-decreasing diameter above a base, each segment sized to be received in a bore of a service cap inserted in the shank of a bit to be repaired. An end-cap for carrying an electronics module includes an end-cap body comprising a bore of similar diameter to the service cap bore diameter, but having one or more lugs protruding radially thereinto to prevent a spindle segment from entering the end cap bore so that the drill bit cannot be supported on the spindle.

TECHNICAL FIELD

The present invention relates generally to an apparatus for use in the repair of drill bits for drilling subterranean formations, and an electronics module end-cap configuration for use therewith.

BACKGROUND

The oil and gas industry expends sizable sums to design rotary drilling and reaming tools, such as downhole drill bits including roller cone or “rock” bits as well as fixed cutter or “drag” bits, which have relatively long service lives, with relatively infrequent failure. In particular, considerable sums are expended to design and manufacture roller cone bits and fixed cutter bits in a manner that minimizes the opportunity for catastrophic drill bit failure during drilling operations. The loss of a roller cone or a polycrystalline diamond compact (PDC) from a fixed cutter bit during drilling operations can impede the drilling operations and, at worst, necessitate rather expensive fishing operations. If the fishing operations fail, sidetrack-drilling operations must be performed in order to drill around the portion of the wellbore that includes the lost roller cones or PDC cutters. Typically, during drilling operations, bits are pulled and replaced with new bits even though significant service could be obtained from the replaced bit. These premature replacements of downhole drill bits are expensive, since each trip out of and back into the well prolongs the overall drilling activity, and consumes considerable manpower. However, they are nevertheless done in order to avoid the far more disruptive and expensive process of, at best, pulling the drill drillstring and replacing the bit or fishing and sidetrack drilling operations necessary if one or more cones or PDC cutters are lost due to bit failure.

With the ever-increasing need for downhole drilling system dynamic data, a number of “subs” (i.e., a sub-assembly incorporated into the drillstring above the drill bit and used to collect data relating to drilling parameters) have been designed and installed in drillstrings. Unfortunately, these subs cannot provide actual data for what is happening operationally at the bit due to their physical placement above the bit itself.

Data acquisition is conventionally accomplished by mounting a sub in the bottom hole assembly (BHA), which may be several feet to tens of feet away from the bit. Data gathered from a sub this far away from the bit may not accurately reflect what is happening directly at the bit while drilling occurs. Often, this lack of data leads to conjecture as to what may have caused a bit to fail or why a bit performed so well, with no directly relevant facts or data to correlate to the performance of the bit.

Recently, data acquisition systems have been proposed to install in the drill bit itself. However, data gathering, storing, and reporting from these systems have been limited. In addition, conventional data gathering in drill bits has not had the capability to adapt to drilling events that may be of interest in a manner allowing more detailed data gathering and analysis when these events occur.

However, the assignee of the present invention has developed a data acquisition system for disposition in the drill bit itself and, specifically, in the shank of such a drill bit, to obtain performance data about the bit during its operation in drilling. This data acquisition system is marketed as the DATABIT™ system by Hughes Christensen, an operating unit of Baker Hughes Incorporated. Embodiments of the DATABIT™ system and its manufacture and use are disclosed in U.S. patent application Ser. No. 11/146,934, filed Jun. 7, 2005 and entitled METHOD AND APPARATUS FOR COLLECTING DRILL BIT PERFORMANCE DATA, the disclosure of which application is incorporated in its entirety herein by reference.

As use of this system, which comprises an electronics module received in the bit shank, has become more widespread, there have been occurrences where the module has been inadvertently left in the bit shank while a bit so equipped has undergone repair. Such repair includes heating in a furnace prior to replacement of damaged components such as PDC cutters, causing damage to the module due to thermal degradation. Such damage includes destruction of electronic components, and may initiate rupture of batteries in the module. Thus there is a need during the repair of such drill bits to ensure that the drill bit does not include such a module therein.

BRIEF SUMMARY

Embodiments of the present invention include a safety support pin configured as a spindle and an associated system and process for use when repairing a drill bit having an electronics module module disposed within the bit shank.

Further embodiments of the present invention include an end-cap for carrying an electronics module within a drill bit shank and configured with a bore to prevent the safety support pin spindle from being received in the shank of a drill bit having the end-cap received therein.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 illustrates a conventional drilling rig for performing drilling operations;

FIG. 2 is a perspective view of a conventional matrix-type rotary drag bit;

FIG. 3A is a perspective view of a shank, an exemplary electronics module, and an end-cap;

FIG. 3B is a schematic cross-sectional view of a shank and an end-cap;

FIG. 4 is a drawing of an embodiment of an exemplary electronics module configured as a flex-circuit board enabling formation thereof into an annular ring suitable for disposition in the shank of FIGS. 3A and 3B;

FIG. 5 is a side perspective view of a spindle of the invention;

FIG. 6 is a top view of the spindle of the invention;

FIG. 7 is a perspective view of an end cap body of the present invention; and

FIG. 8 is a transverse cross-sectional view of the end cap body of FIG. 7.

DETAILED DESCRIPTION

The present invention comprises an apparatus and method for use in the repair of a drill bit having a data acquisition system to determine if electronics disposed therein have been removed. As used herein, the terms “data acquisition system” and “electronics module” include and encompass instrumentation for acquiring and storing and, optionally, analyzing data relating to any selected downhole parameter or parameters, including but not limited to drill bit performance, and without limitation to portions of such systems such a sensors, microprocessors, memory, and power sources.

To illustrate an environment for a drill bit with which the present invention may be used during the repair thereof, FIG. 1 depicts an example of an apparatus for performing subterranean drilling operations. A conventional drilling rig 110 includes a derrick 112, a derrick floor 114, a draw works 116, a hook 118, a swivel 120, a Kelly joint 122, and a rotary table 124. A drillstring 140, which includes a drill pipe section 142 and a drill collar section 144, extends downward from the drilling rig 110 into a borehole 100. The drill pipe section 142 may include a number of tubular drill pipe members or strands connected together and the drill collar section 144 may likewise include a plurality of drill collars. In addition, the drillstring 140 may, optionally, include a measurement-while-drilling (MWD) logging subassembly and cooperating mud pulse telemetry data transmission subassembly, which are collectively referred to as an MWD communication system 146, as well as other communication systems known to those of ordinary skill in the art.

During drilling operations, drilling fluid is circulated from a mud pit 160 through a mud pump 162, through a de-surger 164, and through a mud supply line 166 into the swivel 120. The drilling mud (also referred to as drilling fluid) flows through the Kelly joint 122 and into an axial central bore in the drillstring 140. Eventually, it exits through apertures or nozzles, which are located in a drill bit 200, which is connected to the lowermost portion of the drillstring 140 below drill collar section 144. The drilling mud flows back up through an annular space between the outer surface of the drillstring 140 and the inner surface of the borehole 100, to be circulated to the surface where it is returned to the mud pit 160 through a mud return line 168.

A shaker screen (not shown) may be used to separate formation cuttings from the drilling mud before it returns to the mud pit 160. The MWD communication system 146 may utilize a mud pulse telemetry technique to communicate data from a downhole location to the surface while drilling operations take place. To receive data at the surface, a mud pulse transducer 170 is provided in communication with the mud supply line 166. This mud pulse transducer 170 generates electrical signals in response to pressure variations of the drilling mud in the mud supply line 166. These electrical signals are transmitted by a surface conductor 172 to a surface electronic processing system 180, which is conventionally a data processing system with a central processing unit for executing program instructions, and for responding to user commands entered through either a keyboard or a graphical pointing device. The mud pulse telemetry system is provided for communicating data to the surface concerning numerous downhole conditions sensed by well logging and measurement systems that are conventionally located within the MWD communication system 146. Mud pulses that define the data propagated to the surface are produced by equipment conventionally located within the MWD communication system 146. Such equipment typically comprises a pressure pulse generator operating under control of electronics contained in an instrument housing to allow drilling mud to vent through an orifice extending through the drill collar wall. Each time the pressure pulse generator causes such venting, a negative pressure pulse is transmitted to be received by the mud pulse transducer 170. An alternative conventional arrangement generates and transmits positive pressure pulses.

FIG. 2 is a perspective view of an example of a drill bit 200 of a fixed-cutter, or so-called “drag” bit variety, which needs repair after the use thereof. Conventionally, the drill bit 200 includes threads at a shank 210 at the upper extent of the drill bit 200 for connection into the drillstring 140. At least one blade 220 (a plurality are shown) at a generally opposite end from the shank 210 may be provided with a plurality of natural or synthetic diamond cutting elements (PDC cutter shown) 225, arranged along the rotationally leading faces of the blades 220 to effect efficient removal of subterranean formation material as the drill bit 200 is rotated in the borehole 100 (FIG. 1) under applied weight on bit (WOB). A gage pad surface 230 extends upwardly from each of the blades 220, is proximal to, and generally contacts the sidewall of the borehole 100 during drilling operation of the drill bit 200. A plurality of channels 240, termed “junk slots,” extend between the blades 220 and the gage pad surfaces 230 to provide a clearance area for removal of formation chips formed by the cutters 225.

A plurality of gage inserts 235 is provided on the gage pad surfaces 230 of the drill bit 200. Shear cutting gage inserts 235 on the gage pad surfaces 230 of the drill bit 200 provide the ability to actively shear formation material at the sidewall of the borehole 100 and to provide improved gage-holding ability in earth-boring bits of the fixed cutter variety. The drill bit 200 is illustrated as a PDC (“polycrystalline diamond compact”) bit, but the gage inserts 235 of the same or other structure may be equally useful in other fixed cutter or drag bits that include gage pad surfaces 230 for engagement with the sidewall of the borehole 100.

As used herein, the term “drill bit” includes and encompasses any and all rotary bits, including core bits, roller cone bits, fixed cutter bits; including PDC, natural diamond, thermally stable produced (TSP) synthetic diamond, and diamond impregnated bits without limitation, as well as hybrid bits including fixed as well as rotatable cutting structures, eccentric bits, bicenter bits, reamers, reamer wings, and other earth-boring tools configured for acceptance of an electronics module 290 (FIG. 3A).

FIGS. 3A and 3B illustrate an embodiment of a shank 210 secured to a drill bit 200 (not shown), an end-cap 270, and an embodiment of an electronics module 290 (not shown in FIG. 3B). The shank 210 includes a central bore 280 formed through the longitudinal axis of the shank 210. In conventional drill bits 200, this central bore 280 is configured for allowing drilling mud to flow therethrough. In the present invention, at least a portion of the central bore 280 is configured with a diameter sufficient for accepting the electronics module 290 configured in a substantially annular ring, yet without substantially affecting the structural integrity of the shank 210. Thus, the electronics module 290 may be placed down in the central bore 280, about the end-cap 270, which extends through the inside diameter of the annular ring of the electronics module 290 to create a fluid tight annular chamber 260 with the wall of central bore 280 and seal the electronics module 290 in place within the shank 210.

The end-cap 270 includes a cap bore 276 formed therethrough, such that the drilling mud may flow through the end-cap 270, through the central bore 280 of the shank 210 to the other side of the shank 210, and then into the body of drill bit 200. In addition, the end-cap 270 includes a first flange 271 including a first sealing ring 272, near the lower end of the end-cap 270, and a second flange 273 including a second sealing ring 274, near the upper end of the end-cap 270.

FIG. 3B is a schematic cross-sectional view of the end-cap 270 disposed in the shank 210 without the electronics module 290, illustrating the annular chamber 260 formed between the first flange 271, the second flange 273, the end-cap body 275, and the walls of the central bore 280. The first peripheral sealing ring 272 and the second peripheral sealing ring 274 form a protective, fluid tight, seal between the end-cap 270 and the wall of the central bore 280 to protect the electronics module 290 from adverse environmental conditions. The protective seal formed by the first sealing ring 272 and the second sealing ring 274 may also be configured to maintain the annular chamber 260 at approximately atmospheric pressure. FIG. 4 depicts an electronics module 290 fabricated on a flex circuit 292 so as enable deformation thereof into a ring shape for disposition about an end-cap body 275 so as to fit within an annular chamber 260 defined between an end-cap 270 and the wall of central bore 280 of a bit shank 210.

When a drill bit 200 having an end-cap 270 carrying an electronics module 290 needs to be repaired, before any repair process for the drill bit 200 is undertaken, the end-cap 270 having electronics module 290 therein should be removed from the drill bit 200 to ensure that the electronic module 290 will not be damaged.

Illustrated in FIG. 5 is a side perspective view of a spindle 300 for use in the repair of a drill bit 200 (FIG. 2) shown in a perspective view. The spindle 300 may be located on, or secured to, a suitable structure capable of supporting a drill bit 200 and the spindle 300 thereon in a stable fashion during any portion of any bit repair process, such as on a flat base 314. The spindle 300 is attached to the flat base 314 by a circular portion 301 of the spindle 300 being received in an aperture 316 in the flat base 314 with the circular portion 301 being attached by welding and the like to the flat base 314. The spindle 300 includes any desired number of cylindrical annular segments 302, 304, 306, 308, 310, and 312 being located on and protruding upwardly from the flat base 314. Each cylindrical annular segment 302, 304, 306, 308, 310 and 312 has a different diameter to be accepted within a bore of an annular service cap disposed within the central bore 280 of a shank 210 of a drill bit 200 of a particular size commonly used in drilling subterranean formations and configured to receive an end-cap carring an electronics module during use, to hold the drill bit 200 on spindle 300 in an inverted, upright orientation for repair. Common shank sizes include, without limitation, 3½ inches, 6⅝ inches and 7⅝ inches. Each cylindrical annular segment 302, 304, 306, 308, 310, 312 has an upper surface thereof attached to the base of the next cylindrical annular segment located thereabove so that the spindle 300 has cylindrical annular segments of decreasing size located thereon in a stepped configuration from the bottom of the spindle 300 to the top thereof. The largest cylindrical annular segment 302 is located on the bottom of the spindle 300 and the smallest cylindrical annular segment 312 is located on the top of the spindle 300. The spindle 300 and its components may be formed, for example, of 4140 steel or other similar material stable at bit repair furnace temperatures. For a bit repair procedure requiring preheating of the bit, the bit is placed on a spindle 300 and then the resulting assembly is heated in a furnace, in an otherwise conventional preheating process.

Illustrated in FIG. 5 is a top view of the annular segments 302, 304, 306, 308, 310 and 312 of the spindle 300 showing the stacked, stepped-diameter arrangement thereof.

Illustrated in FIG. 7 is an annular end-cap body 400 according to an embodiment of the present invention in a perspective view. Annular end-cap body 400, the configuration of which is substituted in end-cap 270 in lieu of end-cap body 275 illustrated in FIG. 3B, is used with an electronics module 290 in a drill bit 200 to be instrumented. When such a bit is to be repaired, prior to preheating of the drill bit 200 in a furnace to bring the bit body to a desired temperature for removing and replacing cutters, application of hardfacing materials, and other repair procedures requiring an elevated bit body temperature, the end-cap 270 with electronics module 290 should be removed.

If the end-cap 270 with end-cap body configuration 400 is not, however removed, the configuration thereof prevents the drill bit 200 from being placed on the spindle 300. The annular end- cap body 400 includes an exterior surface 402, a bore segment 404 extending through a portion of the interior of the cap 400, a second bore segment 406 extending through a second portion of the interior of the cap 400, and one or more lugs 408 located on the second bore 406 at any desired position thereon so that the lugs 408 extend a predetermined distance radially into the second bore segment 406 of the cap 400. The lugs 408 are generally located in positions opposed from each other around the second bore 406. However, the lugs 408 may be located adjacent each other on the second bore 406. The lugs 408 located on the second bore 406 of the end-cap body 400 extend radially into the interior of the end-cap body 400 a predetermined distance such that the lugs 408 extend into the bore 276 of end-cap body 400 when an end-cap 270 located in the shank 210 of the drill bit 200. When a drill bit 200 has an end-cap 270 with an end-cap body 400 located in the shank 210 thereof with lugs 408 extending into the bore segment 406 of the end-cap 270 installed in the shank 210 of the drill bit 200, the lugs 408 interferingly engage a cylindrical annular segment 312, 310, 308, 306, 304, 302 sized for the particular shank 210 to prevent the drill bit 200 from being securely and correctly situated and seated about the respective cylindrical annular segment 302, 304, 306, 308, 310 and 312 of the spindle 300. In this manner, the lugs 408 of the end-cap body 400 identify a drill bit 200 having an end-cap 270 therein having an electronic module 290 (FIG. 3A) therein, rather than a service cap of similar configuration to end-cap 270 but having an ID into which the spindle segment 302, 304, 306, 308, 310 or 312 will fit, so that the spindle 300 cannot be used to locate and support a drill bit 200 on a spindle 300 for any repair or inspection operation of the drill bit 200 until the end-cap 270 having end-cap body 400 and carrying electronic module 290 thereon is removed from the drill bit 200 and an appropriately sized service cap inserted in shank 210. The end-cap body 400 may be made of any suitable material for use with the drill bit 200 and, in practice, end-cap 270 including first flange 2271, second flange 273 and end-cap body 400 may be formed as a single piece.

Illustrated in FIG. 8 in a transverse cross-sectional view is the end-cap body 400 across the second bore segment 406 including lugs 408 located thereon. The second bore segment 406 includes a diameter, designated “Normal ID,” substantially the same as a bore of a service cap used to mount a drill bit 200 (FIG. 2) on a spindle 300 in a repair operation, while the adjusted inner diameter of bore, designated “Adjusted ID” defined by the lugs 408 is smaller than the bore of the service cap sized for that particular bit shank size to prevent the drill bit 200 from suitably engaging the spindle 300.

While the present invention has been described herein with respect to certain embodiments, those of ordinary skill in the art will recognize and appreciate that it is not so limited. Rather, many additions, deletions, and modifications to the described embodiments may be made without departing from the scope of the invention as hereinafter claimed, including legal equivalents. In addition, features from one embodiment may be combined with features of another embodiment while still being encompassed within the scope of the invention as contemplated by the inventors. 

1. A support apparatus for drill bits having a shank thereon defining a bore, the apparatus comprising: a spindle comprising a plurality of cylindrical annular segments, the spindle attached to a base, each cylindrical annular segment of the plurality of cylindrical annular segments being sized in diameter for being received within a portion of the bore of a different-sized drill bit shank.
 2. The support device assembly of claim 1, wherein each cylindrical annular segment has a diameter different than a diameter of another, next lower cylindrical annular segment of the spindle.
 3. The apparatus of claim 1, wherein a cylindrical annular segment having a largest diameter of the plurality of cylindrical annular segments is attached to the base.
 4. The apparatus of claim 3, wherein a cylindrical annular segment having a smallest diameter of the plurality of cylindrical annular segments forms an uppermost extent of the spindle.
 5. The apparatus of claim 1, wherein each cylindrical annular segment of the plurality of cylindrical annular segments is secured to another cylindrical annular segment, forming a stepped arrangement for the spindle.
 6. A system for determining if a drill bit having a shank includes an electronics module in a shank bore, the system comprising: a spindle attached to a base comprising a plurality of cylindrical annular segments, each cylindrical annular segment secured to at least one adjacent cylindrical annular segment of a different diameter and being sized for seating in a different-sized shank having disposed therein a cap with a bore therethrough, each segment being sized for seating in a cap bore; and at least one cap having a bore sized to receive a cylindrical annular segment, but for at least one lug therein protruding radially inwardly from a wall of the cap bore to prevent such receipt.
 7. The system of claim 6, wherein the cap comprises an end-cap having the bore therethrough and carrying an electronics module installed therein.
 8. A method of determining if a drill bit contains a member in a shank having a bore therethrough, the method comprising; providing a spindle comprising a plurality of cylindrical annular segments, the spindle attached to a base, the spindle having a cylindrical annular segment of the plurality of cylindrical annular segments seating the a portion of the bore of the drill bit; providing a cap having a bore including within the bore of the shank of the drill bit; attempting to place the spindle in the bore of the cap; and determining if the drill bit will seat on a cylindrical annular segment of the spindle.
 9. The method of claim 8, further comprising determining if the drill bit contains a cap carrying an electronics module installed within the shank responsive to whether the drill bit will sear on a cylindrical annular segment of the spindle.
 10. An end-cap for disposition in a shank of a drill bit, the end-cap comprising: an end-cap body having a bore therethrough; a radially extending flange adjacent one end of the end-cap body; another radially extending flange adjacent an opposing end of the end-cap body; a bore through the end-cap body extending from one end thereof to the opposing end; and at least one lug protruding radially inwardly from a wall of the bore.
 11. The end-cap of claim 10, further comprising a peripheral seal element on each flange.
 12. The end-cap of claim 10, further comprising an electronics module carried by the end-cap between the flanges. 